The purpose of the Molecular Embryology and Pathology Core is to provide all projects with routine services that pertain to analysis of tissue work, necessary to carry out the goals of the various projects. This core offers a state-of-the-art facility for embryology and pathology-based research that is both efficient and cost effective. In addition, the Core will provide technical and supervisory expertise on culturing of embryonic lung explants and subsequent analysis of morphology. The routine services provided will include in situ hybridization, immunohistochemistry, microscopic imaging, photography, and stereology including computer three-dimensional reconstruction and morphometry as well as electron microscopy. Providing the latter services under the same "roof' will assure a high standard of quality-control and uniformity in conduct and analysis of experiments in various projects throughout the POI. Core B is located at The Saban Research Institute of Childrens Hospita_ Los Angeles.